I have a '98 eclipse rs, and just getting tired of the ridiculous gas mileage the car puts out, I get around 16-18 in the city driving under 3500 mostly. How come the gas mileage is so bad for a little car, the car is great and all but the fact a full tank only lasts me about a week is meh. I've been trying to sell this car but when people find out the mpg...etc and especially considering the car is slow as hell.

 

well then id suggest starting with a tune up. There is a reason your getting bad gas mileage and it could be attributed to alot of things
- pcv valve (wouldnt be the whole reason but an atributor)
- fuel filter
- poor spark
- o2 sensor
- catalytic converter
- map sensor

and im sure there is other stuff im forgetting

 

air filter

 

Plugs and wires. Do you have a cel?